Composition for forming resist underlayer film for euv lithography

ABSTRACT

There is provided a compositions of resist underlayer films for EUV lithography that is used in a production process of devices employing EUV lithography, that reduces adverse effects caused by EUV, and that has a beneficial effect on the formation of a favorable resist pattern; and a method for forming resist patterns using the composition of resist underlayer films for EUV lithography. A composition for forming a resist underlayer film for an EUV lithography process used in production of a semiconductor device, comprising a novolac resin containing a halogen atom. The novolac resin may include a cross-linkable group composed of an epoxy group, a hydroxy group, or a combination thereof. The halogen atom may be a bromine atom or an iodine atom. The novolac resin may be a reaction product of a novolac resin or an epoxidized novolac resin and a halogenated benzoic acid; or a reaction product of a glycidyloxy novolac resin and diiodosalicylic acid.

TECHNICAL FIELD

The present invention relates to a compositions of resist underlayerfilms for EUV lithography that is used in a production process ofdevices employing EUV lithography, that reduces adverse effects causedby EUV, and that has a beneficial effect on the formation of a favorableresist pattern, and relates to a method for forming resist patternsusing the composition of resist underlayer films for EUV lithography.

BACKGROUND ART

Conventionally, microfabrication has been carried out usingphotolithography techniques in the production of semiconductor devices.The microfabrication is a fabrication process in which a thin film of aphotoresist composition is formed on a substrate to be fabricated suchas a silicon wafer, active rays such as ultraviolet rays are appliedonto the film through a mask pattern with a pattern of a semiconductordevice followed by development, and the substrate to be fabricated suchas a silicon wafer is etched using the obtained photoresist pattern as aprotective film. In recent years, semiconductor devices have beenfurther integrated, and the active rays to be used have had a shorterwavelength from a KrF excimer laser (248 nm) to an ArF excimer laser(193 nm). Such a change raises serious problems due to the effects ofirregular reflections of active rays from a substrate and standingwaves. Thus, a method of providing a bottom anti-reflective coating(BARC) between the photoresist and the substrate as a resist underlayerfilm that suppresses the reflections has been widely employed.

Inorganic bottom anti-reflective coatings made of titanium, titaniumdioxide, titanium nitride, chromium oxide, carbon, α-silicon, or othersubstances and organic bottom anti-reflective coatings composed of alight-absorbing substance and a polymer compound are known as the bottomanti-reflective coatings. The former needs equipment such as a vacuumdeposition system, a CVD system, and a sputtering system for the coatingformation, but the latter has advantages because special equipment isnot required, and there have been many studies on the latter.

Examples of the organic bottom anti-reflective coatings include anacrylic resin bottom anti-reflective coating that includes a hydroxygroup as a cross-linkable group and a light-absorbing group in a singlemolecule (see Patent Document 1) and a novolac resin bottomanti-reflective coating that includes a hydroxy group as across-linkable group and a light-absorbing group in a single molecule(see Patent Document 2).

It is described that physical properties required for the organic bottomanti-reflective coating material are, for example, large absorption oflight and radiation rays, no intermixing with a photoresist layer (beinginsoluble in a resist solvent), no diffusion of a low molecular weightcompound from a bottom anti-reflective coating material into a resistapplied on the bottom anti-reflective coating during application ordrying by heat, and a dry etching rate larger than that of a photoresist(see Non-patent Document 1).

In recent years, as a next-generation photolithography techniquesubsequent to the photolithography technique using the ArF excimer laser(193 nm), an ArF immersion lithography technique by exposure throughwater has been actively studied. However, the photolithography techniqueusing light has been reaching its limit. Hence, an EUV lithographytechnique using EUV (a wavelength of 13.5 nm) has been drawing attentionas a new lithography technique subsequent to the ArF immersionlithography technique.

In the production process of devices employing EUV lithography, adverseeffects caused by an underlying substrate or EUV raise problems that,for example, a resist pattern for the EUV lithography is made into askirt shape or an undercut shape, thus a favorable straight resistpattern cannot be formed, and a sensitivity to EUV is too low to achievesufficient throughput. Thus, the EUV lithography process does notrequire the resist underlayer film (bottom anti-reflective coating)having the anti-reflection properties, but requires a resist underlayerfilm for EUV lithography so as to reduce these adverse effects, to forma favorable straight resist pattern, and to improve the resistsensitivity.

On the resist underlayer film for EUV lithography, a resist is appliedafter the film formation. Thus, as with the bottom anti-reflectivecoating, the resist underlayer film for EUV lithography requires thecharacteristics of no intermixing with the resist layer (being insolublein a resist solvent) and no diffusion of a low molecular weight compoundfrom a bottom anti-reflective coating material into a resist applied onthe bottom anti-reflective coating during application or drying by heat.

In the generation using the EUV lithography, the resist pattern has anextremely small width, and hence the resist for EUV lithography isrequired to be a thinner film. To address this, the time for a removalprocess of an organic bottom anti-reflective coating by etching isrequired to be significantly reduced, and this requires a resistunderlayer film for EUV lithography that can be used as a thin film or aresist underlayer film for EUV lithography that provides a largeselection ratio of the etching rate with respect to that of a resist forEUV lithography.

RELATED ART DOCUMENTS Patent Documents

Patent Document 1: U.S. Pat. No. 5,919,599 specification Patent Document2: U.S. Pat. No. 5,693,691 specification

Non-Patent Documents

Non-patent Document 1: Proc. SPIE, Vol. 3678, 174-185 (1999)

Non-patent Document 2: Proc. SPIE, Vol. 3678, 800-809 (1999)

Non-patent Document 3: Proc. SPIE, Vol. 2195, 225-229 (1994)

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

The present invention provides a composition for forming a resistunderlayer film for EUV lithography that is used in an EUV lithographyprocess in the production of semiconductor devices. The presentinvention also provides a resist underlayer film for EUV lithographythat reduces adverse effects caused by an underlying substrate or EUV toform a favorable straight resist pattern, that can improve the resistsensitivity, that does not cause intermixing with a resist layer, andthat has a dry etching rate larger than that of a resist. The presentinvention further provides a method for forming a resist pattern for EUVlithography that uses the composition for forming a resist underlayerfilm for EUV lithography.

Means for Solving the Problem

The present invention provides, as a first aspect, a composition forforming a resist underlayer film for an EUV lithography process used inproduction of a semiconductor device including a novolac resincontaining a halogen atom;

as a second aspect, the composition for forming a resist underlayer filmaccording to the first aspect, in which the novolac resin containing ahalogen atom includes a cross-linkable group composed of an epoxy group,a hydroxy group, or a combination of an epoxy group and a hydroxy group;

as a third aspect, the composition for forming a resist underlayer filmaccording to the first aspect or the second aspect, in which the halogenatom is a bromine atom or an iodine atom;

as a fourth aspect, the composition for forming a resist underlayer filmaccording to any one of the first aspect to the third aspect, in whichthe novolac resin containing a halogen atom is a reaction product of anovolac resin or an epoxidized novolac resin and a halogenated benzoicacid;

as a fifth aspect, the composition for forming a resist underlayer filmaccording to any one of the first aspect to the third aspect, in whichthe novolac resin containing a halogen atom is a reaction product of aglycidyloxy novolac resin and diiodosalicylic acid;

as a sixth aspect, the composition for forming a resist underlayer filmaccording to any one of the first aspect to the fifth aspect, in whichthe composition includes the novolac resin containing a halogen atom, across-linking agent, a cross-linking catalyst, and a solvent;

as a seventh aspect, the composition for forming a resist underlayerfilm according to any one of the first aspect to the sixth aspectfurther including an acid generator;

as an eighth aspect, the composition for forming a resist underlayerfilm according to any one of the first aspect to the seventh aspect, inwhich the novolac resin containing a halogen atom is a novolac resinhaving a weight average molecular weight of 1,000 to 100,000;

as a ninth aspect, a resist underlayer film for an EUV lithographyprocess used in production of a semiconductor device, obtained byapplying the composition for forming a resist underlayer film asdescribed in any one of the first aspect to the eighth aspect onto asubstrate and baking the composition; and

as a tenth aspect, a method for producing a semiconductor deviceincluding the steps of applying the composition for forming a resistunderlayer film for EUV lithography as described in any one of the firstaspect to the eighth aspect onto a substrate having a film to befabricated for forming a transferring pattern and baking the compositionso as to form a resist underlayer film for EUV lithography; and applyinga resist for EUV lithography onto the resist underlayer film for EUVlithography, irradiating, with EUV through a mask, the resist underlayerfilm for EUV lithography and a film of the resist for EUV lithography onthe resist underlayer film, developing the film of the resist for EUVlithography, and transferring an image formed in the mask onto thesubstrate by dry etching so as to form an integrated circuit device.

Effects of the Invention

A resist underlayer film that is obtained from the composition forforming a resist underlayer film for EUV lithography of the presentinvention reduces adverse effects caused by an underlying substrate orEUV to form a favorable straight resist pattern and can improve theresist sensitivity. The resist underlayer film has a dry etching ratelarger than that of a resist film formed as the upper layer and canreadily transfer a resist pattern to an underlying film to be fabricatedby a dry etching process.

Furthermore, the underlayer film formed using the composition forforming a resist underlayer film for EUV lithography of the presentinvention has excellent adhesion to a resist film or an underlying film.

The resist underlayer film for EUV lithography of the present inventionis formed beneath a resist film for EUV lithography to improve theresist sensitivity during EUV irradiation and can form a clear resistpattern without requiring the effect of preventing reflected light, incontrast to the resist underlayer film (bottom anti-reflective coating)that is used in a photolithography process in order to prevent thereflected light generated from a substrate.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention is a composition for forming a resist underlayerfilm for EUV lithography that is used in the production of semiconductordevices using EUV lithography technique and that includes a novolacresin having a repeating unit structure containing a halogen atom and asolvent. The composition for forming a resist underlayer film for EUVlithography of the present invention is used in order to form a resistunderlayer film between an underlying film, to which a resist pattern istransferred, on a substrate and the resist film.

The present invention is the composition for forming a resist underlayerfilm for an EUV lithography process that is used in the production ofsemiconductor devices and that includes a novolac resin containing ahalogen atom. The novolac resin includes a cross-linkable group composedof an epoxy group, a hydroxy group, or a combination thereof. There arecases in which the novolac resin includes a repeating unit structurecontaining a halogen atom in which a cross-linkable group is present, orthe novolac resin includes a repeating unit structure containing ahalogen atom and a repeating unit structure containing a cross-linkablegroup. The cross-linkable group may be introduced to a main chain and/ora side chain of the novolac resin.

The introduced cross-linkable group may cause cross-linking reactionwith a cross-linking agent component introduced in the composition forforming a resist underlayer film of the present invention during heatbaking. The resist underlayer film formed by such a cross-linkageforming reaction can prevent the intermixing with a resist film appliedas the upper layer.

The composition for forming a resist underlayer film includes thenovolac resin and a solvent and may further include a cross-linkingagent, a cross-linking catalyst, and a surfactant.

The composition for forming a resist underlayer film for EUV lithographyof the present invention has a solid content of 0.1 to 50% by mass andpreferably 0.5 to 30% by mass. The solid content is a residue that isobtained by removing a solvent component from the composition forforming a resist underlayer film for EUV lithography.

The composition for forming a resist underlayer film for EUV lithographyincludes the novolac resin in an amount of 20% by mass or more, forexample, 20 to 100% by mass, 30 to 100% by mass, 50 to 90% by mass, or60 to 80% by mass, in the solid content.

The novolac resin contains a halogen atom in an amount of at least 10%by mass, preferably 10 to 80% by mass, and more preferably 20 to 70% bymass.

The halogen atom is a fluorine atom, a chlorine atom, a bromine atom, oran iodine atom, and in particular, the halogen atom is preferably abromine atom, an iodine atom, or a combination thereof.

The novolac resin can be obtained by a reaction of a hydroxy group of anovolac resin or a functional group derived from the hydroxy group and acompound containing a halogen atom. Examples of the functional groupderived from the hydroxy group include an oxyglycidyl group that isobtained by a reaction of a hydroxy group and epichlorohydrin. Thecompound containing a halogen atom preferably includes a functionalgroup that reacts with a hydroxy group or an epoxy group of the novolacresin, such as a hydroxy group and a carboxy group. Examples of thecompound containing a halogen atom include bromophenol, bromocatechol,bromoresorcinol, bromohydroquinone, dibromophenol, dibromocatechol,dibromoresorcinol, dibromohydroquinone, iodophenol, iodocatechol,iodoresorcinol, iodohydroquinone, diiodophenol, diiodocatechol,diiodoresorcinol, diiodohydroquinone, bromobenzoic acid, dibromobenzoicacid, tribromobenzoic acid, iodobenzoic acid, diiodobenzoic acid,tribromobenzoic acid, bromosalicylic acid, dibromosalicylic acid,tribromosalicylic acid, iodosalicylic acid, diiodosalicylic acid, andtriiodosalicylic acid.

A reaction product of a novolac resin and a halogenated benzoic acid isexemplified, and a reaction product of an epoxidized novolac resin and ahalogenated benzoic acid is exemplified. Examples of the epoxidizednovolac resin include a glycidyloxy novolac resin, and examples of thehalogenated benzoic acid include dibromobenzoic acid, diiodobenzoicacid, dibromosalicylic acid, and diiodosalicylic acid.

The novolac resin has a weight average molecular weight of 500 to1,000,000, preferably 700 to 500,000, even more preferably 1,000 to300,000, and further more preferably 1,000 to 100,000.

Specific examples of the novolac resin include the following compounds.

In the composition for forming a resist underlayer film for EUVlithography of the present invention, the content (% by mass) of ahalogen atom contained in the polymer compound in the composition may bevaried. That is, the content (% by mass) of a halogen atom contained inthe polymer compound can be changed, for example, by the selection of acompound to be reacted with the polymer obtained by polymerizationreaction of the polymer compound, and the selection of the number andthe type of a halogen atom contained. Then, the use of polymer compoundshaving different halogen atom contents (% by mass) can change thehalogen atom content (% by mass) in the solid content of the compositionfor forming a resist underlayer film, namely, can change the halogenatom content (% by mass) in the resist underlayer film after filmformation. The change of the halogen atom content (% by mass) in theresist underlayer film after film formation can change resistsensitivity and a resist profile. Here, the solid content of thecomposition for forming a resist underlayer film is a component that isobtained by removing a solvent component from the composition forforming a resist underlayer film, and the halogen atom content (% bymass) in the resist underlayer film after film formation is a halogenatom content (% by mass) in the solid content of the composition forforming a resist underlayer film.

The composition for forming a resist underlayer film of the presentinvention is preferably cross-linked by heating after application inorder to prevent the intermixing with a photoresist as an overcoat, andthe composition for forming a resist underlayer film of the presentinvention may further include a cross-linking agent component. Examplesof the cross-linking agent include a melamine compound and a substitutedurea compound having a cross-linkable substituent such as a methylolgroup and a methoxymethyl group and a polymer compound having an epoxygroup. A cross-linking agent having at least two cross-linkablesubstituents is preferred, and examples thereof include compounds suchas a methoxymethylated glycoluril and a methoxymethylated melamine.Tetramethoxymethylglycoluril and hexamethoxymethylolmelamine areparticularly preferred. The additive amount of the cross-linking agentvaries depending on a coating solvent to be used, an underlyingsubstrate to be used, a solution viscosity to be required, a film shapeto be required, or the like, but is 0.001 to 20% by mass, preferably0.01 to 15% by mass, and more preferably 0.05 to 10% by mass, based on100% by mass of the total composition. The cross-linking agent may causecross-linking reaction by self-condensation, but, when a cross-linkablesubstituent is present in the novolac resin that is used in thecomposition for forming a resist underlayer film of the presentinvention, the cross-linking agent can cause the cross-linking reactionwith the cross-linkable substituent.

As a catalyst for accelerating the cross-linking reaction, thecomposition may include an acidic compound such as p-toluenesulfonicacid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonate,salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, andhydroxybenzoic acid and/or a thermal acid generator such as2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, and 2-nitrobenzyltosylate. The combination amount is 0.02 to 10% by mass and preferably0.04 to 5% by mass based on 100% by mass of the total solid content.

The composition for forming a resist underlayer film for EUV lithographyof the present invention may include an acid generator that generates anacid by EUV irradiation, in order to match the acidity to that of aresist applied as the upper layer in a lithography process. Preferredexamples of the acid generator include onium salt compound acidgenerators such as bis(4-tert-butylphenyl)iodoniumtrifluoromethanesulfonate and triphenylsulfoniumtrifluoromethanesulfonate; halogen-containing compound acid generatorssuch as phenyl-bis(trichloromethyl)-s-triazine; and sulfonic acidcompound acid generators such as benzoin tosylate andN-hydroxysuccinimide trifluoromethanesulfonate. The additive amount ofthe acid generator is 0.02 to 3% by mass and preferably 0.04 to 2% bymass based on 100% by mass of the total solid content.

A rheology control agent, an adhesion assistant, a surfactant, and thelike may further be added to the composition for forming a resistunderlayer film for EUV lithography of the present invention asnecessary in addition to the above components.

The rheology control agent is added mainly in order to improveflowability of the composition for forming a resist underlayer film.Specific examples include phthalic acid derivatives such as dimethylphthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate,and butyl isodecyl phthalate; adipic acid derivatives such as di-n-butyladipate, diisobutyl adipate, diisooctyl adipate, and octyl decyladipate; maleic acid derivatives such as di-n-butyl maleate, diethylmaleate, and dinonyl maleate; oleic acid derivatives such as methyloleate, butyl oleate, and tetrahydrofurfuryl oleate; and stearic acidderivatives such as n-butyl stearate and glyceryl stearate. The rheologycontrol agent is commonly included in a ratio of less than 30% by massbased on 100% by mass of the total composition of the composition forforming a resist underlayer film.

The adhesion assistant is added mainly in order to improve adhesionbetween a substrate or a photoresist and the composition for forming aresist underlayer film, in particular, in order not to remove thephotoresist during development. Specific examples include chlorosilanessuch as trimethylchlorosilane, dimethylvinylchlorosilane,methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane;alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane,methyldimethoxysilane, dimethylvinylethoxysilane,diphenyldimethoxysilane, and phenyltriethoxysilane; silazanes such ashexamethyldisilazane, N,N′-bis(trimethylsilyl)urea,dimethyltrimethylsilylamine, and trimethylsilylimidazole; silanes suchas vinyltrichlorosilane, γ-chloropropyltrimethoxysilane,γ-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane;heterocyclic compounds such as benzotriazole, benzimidazole, indazole,imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole,2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, andmercaptopyrimidine; ureas such as 1,1-dimethylurea and 1,3-dimethylurea;and thiourea compounds. The adhesion assistant is commonly included in aratio of less than 5% by mass and preferably less than 2% by mass basedon 100% by mass of the total composition of the composition for forminga resist underlayer film.

The composition for forming a resist underlayer film for EUV lithographyof the present invention may include a surfactant in order not togenerate pinholes or striation and in order to further improve coatingproperties to surface irregularity. Examples of the surfactant include:nonionic surfactants including polyoxyethylene alkyl ethers such aspolyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether,polyoxyethylene alkylallyl ethers such as polyoxyethylene octylphenolether and polyoxyethylene nonylphenol ether,polyoxyethylene/polyoxypropylene block copolymers, sorbitan fatty acidesters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan monooleate, sorbitan trioleate, and sorbitantristearate, and polyoxyethylene sorbitan fatty acid esters such aspolyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, and polyoxyethylene sorbitan tristearate;fluorochemical surfactants including EFTOP EF301, EF303, EF352(manufactured by Tohkem Products Corp.), MEGAFAC F171, F173(manufactured by Dainippon Ink and Chemicals, Inc.), Fluorad FC430,FC431 (manufactured by Sumitomo 3M Ltd.), and Asahiguard AG710, SurflonS-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AsahiGlass Co., Ltd.); and organosiloxane polymer KP 341 (manufactured byShin-Etsu Chemical Co., Ltd.). The compounding amount of the surfactantis commonly 0.2% by mass or less and preferably 0.1% by mass or lessbased on 100% by mass of the total composition of the composition forforming a resist underlayer film of the present invention. Thesesurfactants may be added singly or in combination of two or more ofthem.

Examples of the solvent dissolving the polymer include ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, methyl cellosolveacetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether,diethylene glycol monoethyl ether, propylene glycol, propylene glycolmonomethyl ether, propylene glycol monomethyl ether acetate, propyleneglycol propyl ether acetate, toluene, xylene, methyl ethyl ketone,cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, ethyl 3-ethoxypropionate, methyl3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate,butyl acetate, ethyl lactate, and butyl lactate. These organic solventsare used singly or in combination of two or more of them.

High-boiling solvents such as propylene glycol monobutyl ether andpropylene glycol monobutyl ether acetate may be mixed to be used. Amongthese solvents, propylene glycol monomethyl ether, propylene glycolmonomethyl ether acetate, ethyl lactate, butyl lactate, andcyclohexanone are preferred in order to improve leveling properties.

An EUV resist that is applied as the upper layer of the resistunderlayer film for EUV lithography of the present invention may bepositive or negative. Examples of the resist include a chemicallyamplified resist composed of an acid generator and a binder having agroup that is degraded by an acid to change an alkali dissolution rate,a chemically amplified resist composed of an alkali soluble binder, anacid generator, and a low molecular weight compound that is degraded byan acid to change the alkali dissolution rate of a resist, a chemicallyamplified resist composed of an acid generator, a binder having a groupthat is degraded by an acid to change an alkali dissolution rate, and alow molecular weight compound that is degraded by an acid to change thealkali dissolution rate of a resist, a non-chemically amplified resistcomposed of a binder having a group that is degraded by EUV to change analkali dissolution rate, and a non-chemically amplified resist composedof a binder having a moiety that is cleaved by EUV to change an alkalidissolution rate.

Examples of usable developer for a positive resist having a resistunderlayer film that is formed by using the composition for forming aresist underlayer film for EUV lithography of the present inventioninclude aqueous solutions of alkalis including: inorganic alkalis suchas sodium hydroxide, potassium hydroxide, sodium carbonate, sodiumsilicate, sodium metasilicate, and aqueous ammonia; primary amines suchas ethylamine and n-propylamine; secondary amines such as diethylamineand di-n-butylamine; tertiary amines such as triethylamine andmethyldiethylamine; alcohol amines such as dimethylethanolamine andtriethanolamine; quaternary ammonium salts such as tetramethylammoniumhydroxide, tetraethylammonium hydroxide, and choline; and cyclic aminessuch as pyrrole and piperidine. To the above aqueous alkali solutions,an alcohol such as isopropyl alcohol or a surfactant such as a nonionicsurfactant in a suitable amount may be added for use. Among thosedevelopers, the quaternary ammonium salts are preferred, andtetramethylammonium hydroxide and choline are more preferred.

The resist underlayer film formed from the composition for forming aresist underlayer film for EUV lithography containing the novolac resinhaving a repeating unit structure containing a halogen atom of thepresent invention includes a halogen atom and therefore has acomparatively large dry etching rate. The dry etching rate can becontrolled by varying the halogen atom content.

In the present invention, the composition for forming a resistunderlayer film for EUV lithography is applied onto a substrate andbaked to form a resist underlayer film for EUV lithography.

In the present invention, a semiconductor device is produced by a stepof applying the composition for forming a resist underlayer film for EUVlithography onto a substrate having a film to be fabricated for forminga transferring pattern and baking the composition so as to form a resistunderlayer film for EUV lithography, and a step of applying a resist forEUV lithography onto the resist underlayer film for EUV lithography,irradiating, with EUV through a mask, the resist underlayer film for EUVlithography and a film of the resist for EUV lithography on the resistunderlayer film, developing the resist film for EUV lithography, andtransferring an image formed in the mask onto the substrate by dryetching so as to form an integrated circuit device.

A semiconductor device to which the composition for forming a resistunderlayer film for EUV lithography of the present invention is appliedhas a structure composed of, on a substrate, a film to be fabricated towhich a pattern is transferred, a resist underlayer film, and a resistin this order. The resist underlayer film is formed by applying thecomposition for forming a resist underlayer film for EUV lithographythat includes a polymer compound having a repeating unit structurecontaining a halogen atom and a solvent to the film to be fabricated towhich a pattern is transferred and heat treating the composition. Theresist underlayer film reduces adverse effects caused by an underlyingsubstrate or EUV to form a favorable straight resist pattern, and cangive a margin sufficient to the amount of EUV irradiation. The resistunderlayer film has a dry etching rate larger than that of a resist filmformed as the upper layer and can readily transfer a resist pattern toan underlying film to be fabricated by a dry etching process.

EXAMPLES Synthetic Example 1

In 183.8 g of propylene glycol monomethyl ether, 6.0 g of an epoxidizedcresol novolac resin and 9.7 g of 3,5-diiodosalicylic acid weredissolved, and then 0.23 g of benzyltriethylammonium was added. Thewhole was reacted at the reflux temperature for 24 hours to give asolution of a polymer compound having a repeating unit structure ofFormula (2-1). The obtained polymer compound was subjected to GPCanalysis. The weight average molecular weight of the obtained polymercompound was 3,700 in terms of standard polystyrene.

Synthetic Example 2

In 285.3 g of propylene glycol monomethyl ether, 30.0 g of an epoxidizedphenol novolac resin and 40.4 g of 3,5-dibromobenzoic acid weredissolved, and then 0.91 g of benzyltriethylammonium was added. Thewhole was reacted at the reflux temperature for 24 hours to give asolution of a polymer compound having a repeating unit structure ofFormula (2-2). The obtained polymer compound was subjected to GPCanalysis. The weight average molecular weight of the obtained polymercompound was 1,800 in terms of standard polystyrene.

Synthetic Example 3

In 177.7 g of propylene glycol monomethyl ether, 6.0 g of an epoxidizedcresol novolac resin, 7.3 g of 3,5-diiodosalicylic acid, and 0.8 g ofsalicylic acid were dissolved, and then 0.23 g of benzyltriethylammoniumwas added. The whole was reacted at the reflux temperature for 24 hoursto give a solution of a polymer compound having a repeating unitstructure of Formula (2-3-1) and a repeating unit structure of Formula(2-3-2). The obtained polymer compound was subjected to GPC analysis.The weight average molecular weight of the obtained polymer compound was3,500 in terms of standard polystyrene.

Example 1

Into 10 g of a propylene glycol monomethyl ether solution containing 2 gof the polymer compound obtained in Synthetic Example 1, 0.5 g oftetrabutoxymethylglycoluril, 0.01 g of p-toluenesulfonic acid, 0.04 g ofpyridinium p-toluenesulfonate, and 0.004 g of MEGAFAC R-30 (surfactant,manufactured by Dainippon Ink and Chemicals, Inc.) were mixed. Themixture was dissolved in 49.8 g of propylene glycol monomethyl ether,16.5 g of propylene glycol monomethyl ether acetate, and 8.3 g ofcyclohexanone to make a solution. Then, the solution was filtered usinga polyethylene microfilter having a pore diameter of 0.10 μm and furtherfiltered using a polyethylene microfilter having a pore diameter of 0.05μm to prepare a composition for forming a resist underlayer film.

Example 2

Into 10 g of a propylene glycol monomethyl ether solution containing 2 gof the polymer compound obtained in Synthetic Example 2, 0.5 g oftetrabutoxymethylglycoluril, 0.01 g of p-toluenesulfonic acid, 0.04 g ofpyridinium p-toluenesulfonate, and 0.004 g of MEGAFAC R-30 (surfactant,manufactured by Dainippon Ink and Chemicals, Inc.) were mixed. Themixture was dissolved in 49.8 g of propylene glycol monomethyl ether,16.5 g of propylene glycol monomethyl ether acetate, and 8.3 g ofcyclohexanone to make a solution. Then, the solution was filtered usinga polyethylene microfilter having a pore diameter of 0.10 μm and furtherfiltered using a polyethylene microfilter having a pore diameter of 0.05μm to prepare a composition for forming a resist underlayer film.

Example 3

Into 10 g of a propylene glycol monomethyl ether solution containing 2 gof the polymer compound obtained in Synthetic Example 3, 0.5 g oftetrabutoxymethylglycoluril, 0.01 g of p-toluenesulfonic acid, 0.04 g ofpyridinium p-toluenesulfonate, and 0.004 g of MEGAFAC R-30 (surfactant,manufactured by Dainippon Ink and Chemicals, Inc.) were mixed. Themixture was dissolved in 49.8 g of propylene glycol monomethyl ether,16.5 g of propylene glycol monomethyl ether acetate, and 8.3 g ofcyclohexanone to make a solution. Then, the solution was filtered usinga polyethylene microfilter having a pore diameter of 0.10 μm and furtherfiltered using a polyethylene microfilter having a pore diameter of 0.05μm to prepare a composition for forming a resist underlayer film.

In Table 1, for the measurement of the ratio of dry etching rate of theapplied underlayer film of the present invention to a resist (resistunderlayer film/resist), CF₄ gas was used as the etching gas.

TABLE 1 Ratio of dry etching rate (resist underlayer film/resist film)Example 1 1.3 Example 2 1.3 Example 3 1.3

(Resist Pattern Formation Test)

The solution obtained in Example 1 was applied onto a bare silicon waferwith a spinner. The coated silicon wafer was heated on a hot plate at205° C. for 1 minute to form a resist underlayer film for EUVlithography (a film thickness of 0.03 μm). Onto the resist underlayerfilm for EUV lithography, a resist solution for EUV lithography(polyhydroxystyrene type) was applied with a spinner and heated on a hotplate to form a resist film (a film thickness of 0.08 μm). To the film,EUV exposure was carried out using an EUV exposure apparatusmanufactured by CANON through a mask having a light passing pattern sothat the line width of the resist would have a dense line of 0.045 μm or0.032 μm after development. Next, the wafer was heated on a hot plateagain, then cooled, and subsequently developed using an alkali developerfor 60 seconds. The obtained resist pattern was observed under ascanning electron microscope. The optimum exposure amount was 11.68mJ/cm² or 12.25 mJ/cm² for the formation of a dense pattern of 0.045 μmor 0.032 μm, respectively.

In contrast, when onto a bare silicon wafer, a resist for EUVlithography was applied and then a resist pattern was formed, the amountof EUV irradiation energy was 12.53 mJ/cm² for 0.045 μm and was 13.21mJ/cm² for 0.032 μm. The results show that the resist underlayer filmfor EUV lithography formed from the composition for forming a resistunderlayer film for EUV lithography of the present invention reducesadverse effects caused by an underlying substrate or EUV so that theresist sensitivity can be improved, and also has a dry etching ratelarger than that of a resist.

The embodiments of the composition for forming a resist underlayer filmfor EUV lithography of the present invention have been described above,but the technical scope of the present invention is not limited to thescope described in the embodiments. Various modifications orimprovements may be made to the embodiments.

INDUSTRIAL APPLICABILITY

The present invention can provide: the composition of a resistunderlayer film for EUV lithography that is used in a production processof devices employing EUV lithography, that reduces adverse effectscaused by an underlying substrate or EUV, and that has a beneficialeffect on the formation of a favorable resist pattern; and the methodfor forming a resist pattern that uses the composition of a resistunderlayer film for EUV lithography.

1. A composition for forming a resist underlayer film for an EUVlithography process used in production of a semiconductor device, thecomposition comprising: a novolac resin containing a halogen atom. 2.The composition for forming a resist underlayer film according to claim1, wherein the novolac resin containing a halogen atom includes across-linkable group composed of an epoxy group, a hydroxy group, or acombination of an epoxy group and a hydroxy group.
 3. The compositionfor forming a resist underlayer film according to claim 1, wherein thehalogen atom is a bromine atom or an iodine atom.
 4. The composition forforming a resist underlayer film according to claim 1, wherein thenovolac resin containing a halogen atom is a reaction product of anovolac resin or an epoxidized novolac resin and a halogenated benzoicacid.
 5. The composition for forming a resist underlayer film accordingto claim 1, wherein the novolac resin containing a halogen atom is areaction product of a glycidyloxy novolac resin and diiodosalicylicacid.
 6. The composition for forming a resist underlayer film accordingto claim 1, wherein the composition includes the novolac resincontaining a halogen atom, a cross-linking agent, a cross-linkingcatalyst, and a solvent.
 7. The composition for forming a resistunderlayer film according to claim 1, further comprising an acidgenerator.
 8. The composition for forming a resist underlayer filmaccording to claim 1, wherein the novolac resin containing a halogenatom is a novolac resin having a weight average molecular weight of1,000 to 100,000.
 9. A resist underlayer film for an EUV lithographyprocess used in production of a semiconductor device, obtained byapplying the composition for forming a resist underlayer film as claimedin claim 1 onto a substrate and baking the composition.
 10. A method forproducing a semiconductor device comprising the steps of: applying thecomposition for forming a resist underlayer film for EUV lithography asclaimed in claim 1 onto a substrate having a film to be fabricated forforming a transferring pattern and baking the composition so as to forma resist underlayer film for EUV lithography; and applying a resist forEUV lithography onto the resist underlayer film for EUV lithography,irradiating, with EUV through a mask, the resist underlayer film for EUVlithography and a film of the resist for EUV lithography on the resistunderlayer film, developing the film of the resist for EUV lithography,and transferring an image formed in the mask onto the substrate by dryetching so as to form an integrated circuit device.